Commercial snow plows, front end loaders and snow blowers have a long history of use in removing snow with a blade or edge from streets and highways. Over the past several decades the use of snow plows on light and medium duty trucks has become commonplace. Snow plows work well for clearing snow from roadways, particularly in open places and in areas where yearly snowfall totals are such that the snow can be readily pushed off the roadway. In addition, snow blowers are widely used by people in clearing snow from their yards and sidewalks. There are other uses where a front end loader, a tractor or some other propulsion machine pulls or pushes a tool having a working edge.
One of the issues related to the use of snow clearing machines is that a great amount of stress is imparted to the structural components when plowing in areas such as those prone to frost heaving where manhole covers, and other relatively fixed objects, are struck by a moving scraping edge. Not only do such encounters with immovable objects greatly shorten the life of these snow clearing machines, but they are also quite jarring to the machine operator and pose an enhanced risk of injury to the machine operator as well as others in the vicinity of the machines that are in operation.
Several devices have been developed for use with snow clearing machines, particularly, snow plows, whereby either the whole plow blade, or just a portion of it, pivots back up to about 90 degrees upon encountering a fixed object in the road (see for example U.S. Pat. Nos. 6,701,646 and 5,697,172, respectively). Such devices, while effective for some of the snow plow blades, are not compatible with some other snow clearing machines. For example, due to the different geometry of a loader bucket, the bucket's longitudinal depth combined with the required rear pivotal connections for lifting and dumping prevent such a pivoting back since such pivoting generally requires a pivot point on an angle greater than 45 degrees up from the leading edge. Also, since such buckets typically have a leading edge attached to the horizontal structure of the bucket bottom, the tilting back solutions are impractical because this would require tilting the whole bucket backwards by around 180 degrees. Consequently, there is a need for a device which allows the working edge to ride up over fixed objects upon impacting them, which thereby reduces the wear and tear particularly on snow clearing machines while also enhancing the safety of the machine operator and the public at large.